Don't want to discourage you but frankly if you're a total beginner to create something like ShoeMint with DB loading you've no chance. Unless you want to dedicate a good portion of your life to learning.

Frankly I'd struggle to do that on my own and I've worked on the web since 2005 and free lanced since 08. In Fact if a client approached me wanting that I'd defo team up with the developer I use.

You might be better try to aim at something more realistic.

If you do want to learn you'd need to learn:

HTML
CSS
Javascript
jQuery with Ajax
PHP
Some SQL for the DB

My learning platform of choice is Lynda.com or Code School. Good luck!